. The animal kingdom, arranged after its organization, forming a natural history of animals, and an introduction to comparative anatomy. Zoology. 702 Order II.—HELIANTIIOIDA. This order derives its designation from the resemblance borne by the polypes it includes to a sun-flower or other composite blossom. The common Actinia may be taken as its type ; and all the animals which it includes are constructed nearly upon the same model. The body is composed of a stomach possessing walls of its own, and suspended by vertical partitions which pass in a radiating direction between the outer
. The animal kingdom, arranged after its organization, forming a natural history of animals, and an introduction to comparative anatomy. Zoology. 702 Order II.—HELIANTIIOIDA. This order derives its designation from the resemblance borne by the polypes it includes to a sun-flower or other composite blossom. The common Actinia may be taken as its type ; and all the animals which it includes are constructed nearly upon the same model. The body is composed of a stomach possessing walls of its own, and suspended by vertical partitions which pass in a radiating direction between the outer surface of the stomach and the general integument, so as to divide the intervening space into numerous chambers. The stomach is closed at the bottom, as are also the surrounding chambers; and this is equally the case in the compound species as in the solitary. The radiating parti- tions have openings, by which the chambers communicate with each other • and there is also a free passage from them into the hollow tentacula, which are provided with orifices at the extremity, that can be opened or closed by the animal. Water is sometimes taken in by these orifices, so as to distend the radiating chambers and the tentacula ; and is then ejected with consi- derable force through the same apertures. There is reason to believe that this is a respiratory process ; the whole interior of the chambers, into which the water is received, being covered with vibratile cilia. These chambers, however, are specially intended for the development of the ova. The ovaries Fin. 13 Section of Sea-Anemose : . ... t j i »i ? i j * * .., ... n, envitj ..I Btomach, b surrounding chambers, form plaited masses, attached along the inner border of some of the vertical leaflets which do not extend as far as the stomach. The ova appear to be developed in the substance of these masses, and to escape, by the rupture of the membranous envelope of the ovarium, into the interseptal spaces. The embryo is sometimes
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Keywords: ., bookcentury1800, bookdecade1850, booksubjectzoology, bookyear1854
